1. Field of the Invention
This invention relates to skateboards and more particularly to an improved skateboard having means for contacting a support surface only along the longitudinal centerline of the board.
2. Description of the Prior Art
The term "skateboard" is generally used to refer to a sporting device including an upper, generally horizontal, elongated board for supporting a rider standing on its top surface, and four wheels mounted in pairs on trucks or transverse axles mounted on its bottom surface for limited pivotal steering movement adjacent the front and rear ends, respectively, of the board. The rider stands on the board with his feet extending generally transversely of and spaced apart along its longitudinal axis, and the board is steered by the rider selectively shifting weight to apply more pressure to the wheels on one side or the other of the board. The wheel mounting and steering operation of such prior art skateboards is described, for example, in U.S. Pat. No. 5,160,155.
Skateboards are also known which have only two wheels mounted on the longitudinal centerline of the board one adjacent each end thereof, and one such skateboard is disclosed in the above-mentioned U.S. Pat. No. 5,160,155. In this prior art device, the front wheel is supported by a fork arrangement rotatable about an upwardly extending pivot axis with the wheel contacting the ground rearwardly of the point of intersection of the pivot axis with the ground so as to provide automatic steering on tilting of the board. The rear wheel is mounted for rotation about a fixed axis close to, but rearwardly of the board centerline, with the fixed axis being in the plane of the board so that the upper portion of the wheel projects above the board surface. In use of this skateboard, the rider stands with one foot forward and one foot rearward of the rear wheel, again with both feet extending generally transversely of the board for balance, control and steering.
U.S. Pat. No. 3,995,873 also discloses a skateboard having only two wheels located one near each end and on the longitudinal centerline of the board. In this device, the wheels or rolls have an axial length at least equal to half the width of the board to provide transverse stability for the board. The rolls are mounted and arranged to steer in opposite directions upon tilting of the board. In use, the rider stands on and steers the device in the same manner as conventional four wheel skateboards.
U.S. Pat. No. 5,125,687 discloses a roller board intended to simulate skiing over a road surface. In use of this board, the rider stands with his feet in side-by-side relation extending lengthwise of the board which is supported by a pair of rollers or wheels positioned on its longitudinal axis, one forward of and one near the rear of the rider support surface of the board. A pair of outrigger rollers are mounted one adjacent each lateral edge of the board to limit the tilting movement about the longitudinal roll axis as defined by the main support wheels. Two footholds are provided on the board's top surface, with a raised divider separating the footholds along the longitudinal centerline of the board to accurately position the rider's feet on the board's surface. The front wheel is supported by a caster or fork for steering, with a spring normally biasing the fork to its centered or straight line position. This patent also discloses use of a removable skate blade which may be mounted on the bottom of the board, to adapt the device for use on ice, and suggests the use of a saddle mounted on the board's top surface to allow the rider to sit while maintaining his feet on the generally horizontal surface of the footholds. The rider propels himself by use of a pair of handheld poles.
In the prior art skateboards and rollerboards described above, the stability of the boards carrying a standing rider, particularly during extreme maneuvering, has required a relatively long wheel base which, in turn, has generally required caster mounting or steerable truck mounting of the wheels, or at least the front wheel or wheels for maneuvering.